72 Biomarker testing in patients with newly diagnosed advanced ovarian cancer – results from the first interim analysis of the non-interventional SCOUT-1 study (NOGGO Ov54, NCT04830709)

Introduction/Background Genomic breast cancer gene mutation (BRCAm) increases the risk for hereditary breast and/or ovarian cancer (HBOC). However, BRCAm and other homologous recombination deficiencies (HRD) also render eminent sensitivity of ovarian cancer (OC) to poly-(ADPribose)-polymerase inhibitors (PARPi). Therefore, international guidelines recommend biomarker testing to assess familial risk (blood) and to tailor individual treatment (tumour and/or blood). Real-world management of patients with primary advanced, high-grade, epithelial OC is currently being evaluated by the prospective, non-interventional study SCOUT-1 (NOGGO ov54, NCT04830709). Methodology 750 patients with completed surgery (if applicable), eligible for platinum-based chemotherapy, tested for BRCA1/2m (solitary or within HRD-test) and provided written informed consent, are planned to be enrolled in SCOUT-1 and followed for up to 7 years. Interim analyses (IA) were defined at 175, 250 and 375 enrolled patients followed for at least 6 months. Here we present details on biomarker testing based on data from 1stIA; only descriptive statistical methods were applied. Results Out of 175 patients considered for 1stIA (data cut-off: April 20th, 2023), 159 qualified for the Full Analysis Set (FAS). Burden for HBOC was assessed for 76.7% (N=122 patients); of these 40.2% (N=49) showed increased risk (risk score ≥ 3, DKG checklist). BRCA-test-results (blood and/or tumour) were available for 152 patients (95.6%) and BRCAm was detected in 24.3% (N=37) of the patients tested (30 with BRCA1m; 6 with BRCA2m; 1 with BRCA1 16 (61.5%) of those showed an increased risk for HBOC at assessment of family history. Of all tumours tested (N=62), 45.2% (N=28) were HRD positive. Conclusion The incidence of BRCAm and HRD observed at the time of the 1stIA is consistent with previously published data. Significant number of patients with genomic BRCAm had no increased risk according to HBOC assessment. Number of patients tested for HRD remains low. Disclosures This study is funded by AstraZeneca and is part of an alliance between AstraZeneca and Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA.